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Follow-up on recent Lochinvar Knight Installation

A couple months ago we took out a couple 1MMBTU Weil McLain CI HW boilers and installed 3 500KBTU Knights in one of our buildings (about 45,000 square feet of office space). We've accumulated about 225 hours of runtime on each one, and so far, only one minor problem to report. Occasionally we would have a lockout based on an "open flue sensor." This would occur only when the boiler was operating for an extended time at its minimum 20% load, and we were running a loop temperature between 75 and 85 degrees or so. To me, it seemed that because we were running so efficiently, the flue outlet temp was too close to the water temp and the control algorithm was flagging it as a bad sensor. Lochinvar shipped us 3 new flue sensors to try and there have been no more trips.

Originally, I figured we would save 40 to 50% on our fuel bill, due partly to boiler efficiency, and partly to our ability through this boiler selection to rescale the HW reset schedule significantly lower. We don't have to worry about condensation in the boiler anymore. We want it! I'm happy to report that for the last two months, our consumption has been reduced by 74%. That's right. A reduction of 74 percent. The Weil McLains were tuned well and running cleanly, but the combination of being oversized, non-condensing, loaded with water volume, and short-cycling made the whole system inefficient. The average cycle time on the Knights is about 10 hours. That's the difference modulation makes.

Anyway, we finished the insulation, so here's a couple final pics for the Wall. Feel free to call me with any questions (518) 257-3394. Happy Holidays everyone.

Bob McRae
New York State Dormitory Authority
Albany, NY


  • Brad White_149
    Brad White_149 Member Posts: 24
    What great news, Bob!

    Not only for the students and taxpayers but for the industry to illustrate what can be done with commercially available equipment.

    I thank you for checking back in with a thorough and informative report, Bob.

    Please keep us posted.

    Question, not to be a fly in the ointment- how if at all are you treating the condensate heading into that trench drain. Does it go eventually to a chip tank? Curious.


    Can you imagine what effect it would have on the environment if all commercial buildings would reduce their energy consumption for heating by 74%..

    Great job there.

  • Xc8p2dC_2
    Xc8p2dC_2 Member Posts: 150
    Impressivei Install

    Sadly, my CI boiler, created so much anxiety, I had to put rolls of toilet paper next to mine as well,,,,, only kiddin ya>> looks sweet
  • Kevin O. Pulver
    Kevin O. Pulver Member Posts: 380

    Bob, I remember your earlier post. It's a shame to put insulation on all that gorgeous copper work.
    I appreciate your follow up here as I have several of these installed (new construction, so no before/after comparison) and can use your information as a comparison for sales. I don't care if these are the only kind I ever install. I love them.

    Brad, I think someone talked about crushed limestone in the trench drain on the earlier post. (maybe yourself?)

    Bob, has the gas company come around to change your gas meter? They gotta notice that something is "wrong" when they check your bill! Thanks again, Kevin

  • Thanks for all the great comments and compliments guys. I'll pass them along to my fellow workers involved with me in the installation.

    Funny thing about the gas meter -- it's a new meter, as I asked for pulse output for datalogging with my building management system. I fully expect National Grid to call me and question their meter! On top of that, we just finished "negotiating" with an esco that won some kind of OGS bid for all state agencies at about the same time we independently signed with a different one. This bid winner was really going to make problems for us, but luckily the other esco took the high road and released us from their contract. I get the last laugh because the "winner" is only going to get about 25% of the volume they anticipated!! HaHa. That's karma at work.

    As far as treating the condensate, we are presently not treating it at all. We have an amount of atmospheric condensate draining into that trench from some telephone room ac units on the other side of the boiler room wall, and that will dilute the boiler condensate somewhat. Also, in our own HQ building, we have (5) 1MMBTU Fulton Pulse condensing boilers draining directly into one cast iron draining system eventually dumping into building sanitary, and after 9 years we have had no problems with disappearing pipe. We will be watching it, though. And we will be regularly flushing the trench with fresh water to keep it clean.
  • Brad White_149
    Brad White_149 Member Posts: 24

    Thanks for the info on that Bob. Yes, as Kevin suggests, I may have mentioned putting marble/limestone chips in the trench (can it hurt?)

    I see what you are saying about dilution with telephone system AC units, but those are mostly sensible cooling devices especially in winter when it is both dry internally and the boilers will be producing most condensate. In other words, I would not count on a reliable volume. Flushing is good, I just prefer passive intervention where I can.

    After 9 years of Fulton use, you may still have your pipe but one never knows how thick the wall is. Not sure how you are watching it. One day it is there, one day it will not be. Just looking out for you!

    But please do not take that as criticism for what is a beautiful installation- It is truly gratifying to see that done on the Public Dime.

  • Larry (from OSHA)
    Larry (from OSHA) Member Posts: 716
    great looking boiler room


    This install really looks wonderful and congratulations on the fantastic reduction in fuel usage.

    A couple of questions if you don't mind. What are the emitters that allow the low temps and how long of a run did the venting end up being?

    Thanks for sharing your project with all here.

  • J.C.A._3
    J.C.A._3 Member Posts: 2,981
    Lets see....

    I'm guessing that between the fuel reduction and the electrcal savings, the install will pay for itself in just about 3 years.(TOPS!)

    Congratulations Bob on a fine project and showing that it REALLY CAN BE DONE! On to the next one. Chris

  • The boilers are used in a VAV w/reheat application. The building is nearly fully automated (we are presently converting pneumatic to ddc throughout) so we are able to float AHU supply air setpoints up in response to overall zone conditions, including damper positions and reheat valve positions. Once we've gotten a maximum AHU supply temp, reheat needs are minimal, hence we can get away with simply "tempering" the air at the zone. We do have a couple cabinet style unit heaters in stairwells and entrance foyers that we will have to increase our gpm through to meet expected requirements, but other than that, there is no need for 140 to 180 degree water per previous design. Our present reset schedule is 70 to 130 degrees, 80 to 0 degrees outside. Incidentally, the original reheat loop design reset schedule in our HQ building was similar to this Delmar building, with a high temp of 180 at 0 degrees. We've been running that system with a maximum of 130 degrees to the reheat coils for 9 years.

    Our venting wound up being directly through the roof, through the 24-inch diameter penetration of the original breeching/stack. I'll attach a couple photos. The exhaust is terminated straight up while the intakes are a couple feet lower and terminated downward. The entire "assembly" is above expected snowline. Each boiler's total combined vent piping length is about 60 feet with about (7) 90 degree ells, including the two used on the intake termination. Boiler 1 is a little less than 60 and boiler 3 is a little more.

  • The project came in just under $35,000 which included every nut and bolt, and a few thousand dollars for the Andover Controls hardware and variable speed drives for the main pumps. It also included about $6K for a piping contractor to fabricate the two 3-inch welded steel headers and re-pipe the entire gas main (3-inch welded also). Unfortunately, we're not certified welders!

    Attached is a photo of the control panel under construction. Note the two pump drives in the lower left. You gotta love how small these babies are getting! There was about $3,000 worth of hardware in that panel.
  • big bill_3
    big bill_3 Member Posts: 5

    a great feature on the KNIGHT IS THE FACT you can stage them with communication wire-up 2 8 thats 4 million btuh, one of the limitations is the 100'restriction on the exhaust
  • Greg Gibbs
    Greg Gibbs Member Posts: 75

    Hey Big Bill, I agree that the 100' vent length (200' ft. combined)really does limit things a bit. :)
    Great venting options w/ the Knight!
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